<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <button>按钮1</button>
    <button>按钮2</button>
    <button>按钮3</button>
    <button>按钮4</button>
    <button>按钮5</button>

    <script>
        /*
         *排他思想：
          先清除掉其他元素
          再设置自己样式 
         */
        //获取所有按钮元素
        var btns = document.getElementsByTagName('button');
        //for循环绑定点击事件
        for (var i = 0; i < btns.length; i++) {
            btns[i].onclick = function () {
                //1.我们先把所有的按钮背景颜色取掉
                for (var i = 0; i < btns.length; i++) {
                    btns[i].style.backgroundColor = '';
                }
                //2.然后才让当前背景颜色为pink
                this.style.backgroundColor = 'pink';
                // console.log(11);

            }
        }
    </script>
</body>

</html>